Google Disavow tool helps you to track the spam or bad backlinks of your website. It does not delete the links for you. You need to manually contact the webmasters to get your links deleted.

Disavow tool help us when we are not able to remove backlinks manually then you can upload this type of links on disavow tool to not consider as a backlinks to our site. So basically it is blocked our bad backlinks which we upload on disavow tool.

Disavow tool is used to remove unnatural or low quality backlinks, but you can not delete these links yourself, you need to supply these low quality backlinks with the help of disavow tool than rest of activity is done by Google.